INA21x

V+

OUT

GND

IN-

IN+

C

BYPASS

0.01 F

m

to

0.1 F

m

2.7 V to 26 V

REF

Reference

Voltage

Supply

Load

R

SHUNT

Output

R

1

R

3

R

2

R

4

INA213-Q1

INA214-Q1

www.ti.com

SBOS475B – MARCH 2009 – REVISED JUNE 2010

APPLICATION INFORMATION

BASIC CONNECTIONS

Figure 23 shows the basic connections of the INA213 or INA214. The input pins, IN+ and IN–, should be

connected as closely as possible to the shunt resistor to minimize any resistance in series with the shunt

resistance.

Figure 23. Typical Application

Power-supply bypass capacitors are required for stability. Applications with noisy or high impedance power

supplies may require additional decoupling capacitors to reject power-supply noise. Connect bypass capacitors

close to the device pins.

POWER SUPPLY

The input circuitry of the INA21x can accurately measure beyond its power-supply voltage, V+. For example, the

V+ power supply can be 5 V, whereas the load power supply voltage can be as high as 26 V. However, the

output voltage range of the OUT terminal is limited by the voltages on the power-supply pin. Note also that the

INA21x can withstand the full –0.3 V to 26 V in the input pins, regardless of whether the device has power

applied or not.

The zero-drift offset performance of the INA21x offers several benefits. Most often, the primary advantage of the

low offset characteristic enables lower full-scale drops across the shunt. For example, non-zero-drift current

shunt monitors typically require a full-scale range of 100 mV.

The INA21x gives equivalent accuracy at a full-scale range on the order of 10 mV. This accuracy reduces shunt

dissipation by an order of magnitude with many additional benefits.

Alternatively, there are applications that must measure current over a wide dynamic range that can take

advantage of the low offset on the low end of the measurement. Most often, these applications can use the lower

gain INA213 or INA214 to accommodate larger shunt drops on the upper end of the scale. For instance, an

INA213 operating on a 3.3-V supply could easily handle a full-scale shunt drop of 60 mV, with only 60 µV of

offset.

UNIDIRECTIONAL OPERATION

Unidirectional operation allows the INA21x to measure currents through a resistive shunt in one direction. The

most frequent case of unidirectional operation sets the output at ground by connecting the REF pin to ground. In

unidirectional applications where the highest possible accuracy is desirable at very low inputs, bias the REF pin

to a convenient value above 50 mV to get the device output swing into the linear range for zero inputs.

Copyright © 2009–2010, Texas Instruments Incorporated

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Product Folder Link(s): INA213-Q1 INA214-Q1